When choosing the sizes of new gutters and pipes, you need to bear in mind the size of your roof and the position of each gutter downpipe so that the system doesn’t overflow. Keep in mind that guttering systems in the UK need to abide by the regulations of BS EN 12056-3:2000 Gravity drainage systems inside buildings. Roof drainage, layout and calculation.
Once you’ve calculated your effective roof area, the question is:
Does guttering come in different widths? And if so, what is the standard residential gutter size?
Depending on the type of guttering, the standard gutter size in the UK can vary from 75mm mini guttering to 200mm industrial guttering supplies. In terms of length, most guttering comes in lengths of 2m or 4m.
Let’s take a closer look at the four main guttering types.
Table of contents
Half-round gutters
Half-round guttering is one of the most enduringly popular styles. You’ll find that the most common half-round gutters in the UK, such as Brett Martin gutters, are 112mm in diameter. However, other sizes are also available, including 100mm, 125mm and more.
Deep gutters
Deep guttering is ideal for areas with extensive rainfall. The most common diameter is 115mm. However, wider gutters of 170mm are also available.
Box gutters
Box guttering, also known as square guttering, consists of a 3-sided rectangular channel. They’re usually 114mm in diameter, as with Brett Martin guttering of this type.
Ogee gutters
Like a box roof gutter, most Ogee gutters are 115mm in diameter, with 106mm being another popular size.
Fun fact:
The word Ogee comes from ‘old gothic’, the style of guttering that was all the rage during the Victorian era.
Roof pitch multiplier table
In this section, you’ll find a conversation table we’ve created to save you time calculating.
The table below shows the following:
- Roof pitch – Measured 12-inch mark out from the roof up to the inside of the roof.
- Roof angle – Incline of the roof in degrees.
- Roof pitch multiplier – Used to help find the surface area of a pitched roof or length of a common rafter.
Note: For roof pitches greater than 18/12, please contact the relevant manufacturer for support.
| Roof pitch | Roof angle (Degrees) | Roof pitch multiplier |
| 1/12 | 4.8 | 1.003 |
| 2/12 | 9.5 | 1.014 |
| 3/12 | 14 | 1.031 |
| 4/12 | 18.4 | 1.054 |
| 5/12 | 22.6 | 1.083 |
| 6/12 | 26.6 | 1.118 |
| 7/12 | 30.3 | 1.158 |
| 8/12 | 33.7 | 1.202 |
| 9/12 | 36.9 | 1.250 |
| 10/12 | 39.8 | 1.302 |
| 11/12 | 42.5 | 1.357 |
| 12/12 | 45 | 1.414 |
| 13/12 | 47.3 | 1.474 |
| 14/12 | 49.4 | 1.537 |
| 15/12 | 51.3 | 1.601 |
| 16/12 | 53.1 | 1.667 |
| 17/12 | 54.8 | 1.734 |
| 18/12 | 56.3 | 1.803 |
Final thoughts
When fitting gutters, it’s important to be mindful of the material they’re made of. While relatively straightforward to install regardless of size, aluminium gutters, copper gutters, plastic gutters, zinc gutters and cast iron gutters all have specific requirements. If in doubt about which type of gutter is best for your project, check out our in-depth guide.
You can also head on over to our guttering buyer’s guide for in-depth advice to make an informed decision prior to purchase.
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